FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/rangecoder.h
Date: 2021-09-24 20:55:06
Exec Total Coverage
Lines: 54 54 100.0%
Branches: 22 22 100.0%
Line Branch Exec Source
1 /*
2 * Range coder
3 * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * Range coder.
25 */
26
27 #ifndef AVCODEC_RANGECODER_H
28 #define AVCODEC_RANGECODER_H
29
30 #include <stdint.h>
31
32 #include "libavutil/common.h"
33 #include "libavutil/avassert.h"
34
35 typedef struct RangeCoder {
36 int low;
37 int range;
38 int outstanding_count;
39 int outstanding_byte;
40 uint8_t zero_state[256];
41 uint8_t one_state[256];
42 uint8_t *bytestream_start;
43 uint8_t *bytestream;
44 uint8_t *bytestream_end;
45 int overread;
46 #define MAX_OVERREAD 2
47 } RangeCoder;
48
49 void ff_init_range_encoder(RangeCoder *c, uint8_t *buf, int buf_size);
50 void ff_init_range_decoder(RangeCoder *c, const uint8_t *buf, int buf_size);
51
52 /**
53 * Terminates the range coder
54 * @param version version 0 requires the decoder to know the data size in bytes
55 * version 1 needs about 1 bit more space but does not need to
56 * carry the size from encoder to decoder
57 */
58 int ff_rac_terminate(RangeCoder *c, int version);
59
60 void ff_build_rac_states(RangeCoder *c, int factor, int max_p);
61
62 1371293360 static inline void renorm_encoder(RangeCoder *c)
63 {
64 // FIXME: optimize
65
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 1455989918 while (c->range < 0x100) {
66
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 84696558 if (c->outstanding_byte < 0) {
67 8249 c->outstanding_byte = c->low >> 8;
68
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 84688309 } else if (c->low <= 0xFF00) {
69 55429362 *c->bytestream++ = c->outstanding_byte;
70
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 55994484 for (; c->outstanding_count; c->outstanding_count--)
71 565122 *c->bytestream++ = 0xFF;
72 55429362 c->outstanding_byte = c->low >> 8;
73
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 29258947 } else if (c->low >= 0x10000) {
74 28582609 *c->bytestream++ = c->outstanding_byte + 1;
75
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 28693822 for (; c->outstanding_count; c->outstanding_count--)
76 111213 *c->bytestream++ = 0x00;
77 28582609 c->outstanding_byte = (c->low >> 8) & 0xFF;
78 } else {
79 676338 c->outstanding_count++;
80 }
81
82 84696558 c->low = (c->low & 0xFF) << 8;
83 84696558 c->range <<= 8;
84 }
85 1371293360 }
86
87 827820 static inline int get_rac_count(RangeCoder *c)
88 {
89 827820 int x = c->bytestream - c->bytestream_start + c->outstanding_count;
90
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 827820 if (c->outstanding_byte >= 0)
91 827438 x++;
92 827820 return 8 * x - av_log2(c->range);
93 }
94
95 1371278274 static inline void put_rac(RangeCoder *c, uint8_t *const state, int bit)
96 {
97 1371278274 int range1 = (c->range * (*state)) >> 8;
98
99 av_assert2(*state);
100 av_assert2(range1 < c->range);
101 av_assert2(range1 > 0);
102
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 1371278274 if (!bit) {
103 583956132 c->range -= range1;
104 583956132 *state = c->zero_state[*state];
105 } else {
106 787322142 c->low += c->range - range1;
107 787322142 c->range = range1;
108 787322142 *state = c->one_state[*state];
109 }
110
111 1371278274 renorm_encoder(c);
112 1371278274 }
113
114 1378588201 static inline void refill(RangeCoder *c)
115 {
116
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 1378588201 if (c->range < 0x100) {
117 84279872 c->range <<= 8;
118 84279872 c->low <<= 8;
119
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 84279872 if (c->bytestream < c->bytestream_end) {
120 84278207 c->low += c->bytestream[0];
121 84278207 c->bytestream++;
122 } else
123 1665 c->overread ++;
124 }
125 1378588201 }
126
127 1378588201 static inline int get_rac(RangeCoder *c, uint8_t *const state)
128 {
129 1378588201 int range1 = (c->range * (*state)) >> 8;
130
131 1378588201 c->range -= range1;
132
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 1378588201 if (c->low < c->range) {
133 587760183 *state = c->zero_state[*state];
134 587760183 refill(c);
135 587760183 return 0;
136 } else {
137 790828018 c->low -= c->range;
138 790828018 *state = c->one_state[*state];
139 790828018 c->range = range1;
140 790828018 refill(c);
141 790828018 return 1;
142 }
143 }
144
145 #endif /* AVCODEC_RANGECODER_H */
146